What ever you think sounds best. Sometimes when I listen to a great system, I forget where I am and get drawn into the musical moment. This illusion usually occurs when the system does not add any distracting sonic effects. I prefer tubes but good solid state also can do it. Musicality it first but you need to be somwhat neutral but not to the point of being clinical.
neutrality vs. realism
What is actually the final goal of high-end audio: to reproduce recorded music as neutral as possible or to give the highest possible level of realism? For some manufacturers (like Spectral and Madrigal) it is the ultimate goal regarding their amplifiers, to sound like no amplifier at all. There is less coloration, less "house sound", more "truthfulness". I think this is a good basic consideration, but it must not derive the sound of it's musicality. Those amplifiers are generally sounding lifeless! Don't get me wrong, this is not about the tubes vs. solid state controverse at all, because I think that solid state amplifiers are able to give a high level of musicality without sacrificing neutrality (Boulder, FM Acoustics). What seems perfect on paper is not always the way to go: "neutrality" and "perfect measurements" are not the synonyms for musicality and realism.